Effects of CO2 enrichment on the anaerobic digestion of sewage sludge in continuously operated fermenters

• Long-term continuous anaerobic digestion experiments treating sewage sludge (> 450 d). Effects of CO 2 enrichment on the process. Significantly increased methane production as immediate response to enrichment. Sustainably enhanced specific at higher organic loading rates. Improved process resilience after disturbance in a -enriched environment. The effect (AD) potential strategy improve biogas yield was assessed increasing rates (OLR). performance and were evaluated long-term AD lab-scale. (SMP) sustainably test digester compared control elevated OLRs, reaching an increase 6 ± 12% average highest OLR tested (4.0 kg VS /(m 3 ·d)). reduction via homoacetogenesis, facilitating acetoclastic CH 4 formation is proposed dominant conversion pathway. Results suggest that sufficient load easily degradable substances prerequisite for intrinsic equivalent H acidogenesis. under conditions acid accumulation further qualifies this approach viable option improving by converting waste stream into valuable product.